In vivo gene transfer to vascular tissue has the potential for treating localized vascular pathology. In our current work we have found that in vivo gene transfer to vascular tissue does occur but only in a very low efficiency when retroviruses are used to deliver the genes into an uninjured artery. In order to increase the efficiency of gene transfer into blood vessels, and since the pathological process that we are investigating is vascular injury with smooth muscle proliferation, we plan to expose injured rabbit ear artery to different modalities of in vivo gene transfer. The efficiency of gene transfer will be assessed initially by amplifying a marker gene sequence that will be delivered to the arterial tissue with the use of handicapped retroviruses. The relevant sequence will be amplified by PCR.